Scholarly Works, School of Plant and Environmental Sciences
Permanent URI for this collection
Browse
Browsing Scholarly Works, School of Plant and Environmental Sciences by Content Type "Technical report"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- Delineation and management of sulfidic materials in Virginia highway corridorsOrndorff, Zenah W.; Daniels, W. Lee (Virginia Center for Transportation Innovation and Research, 2002-09)Excavation through sulfidic geologic materials during road construction has resulted in acid drainage related problems at numerous discrete locations across Virginia. Barren acidic roadbanks, and acidic runoff and fill seepage clearly cause local environmental problems along Virginia road corridors. Degradation of construction materials may necessitate road repairs, which can be time-consuming, costly, and a nuisance to travelers. These problems can be minimized, and even prevented, by incorporating sulfide hazard analysis into the pre-design stage of highway construction. Evaluating the likelihood of encountering sulfidic materials can decrease exposure of problematic materials. When exposure cannot be avoided, proper characterization of the material allows for immediate application of appropriate remediation procedures. Failure to rigorously identify and remediate acid-forming materials in the road planning and construction process will inevitably lead to the mix of engineering and environmental problems discussed and documented in this report. While the barren and erosive slopes resulting from acidification of cut roadbanks are the most obvious indicator of this problem, the long term emission of acidic drainage from fills is clearly the most serious environmental compliance problem that VDOT will face with sulfidic materials over time. Unfortunately, many of these problems (e.g. acid seepage from fills) do not become obvious for some period of time after the road construction contracts have been closed, leaving the full liability for environmental compliance resting upon VDOT maintenance budgets. Therefore, the true cost of identifying, handling and disposing of potentially acid-forming materials must be rigorously assessed and designed for in the road building process.
- Effects of Soil Amendments and Other Practices Upon the Success of the Virginia Department of Transportation's Non-Tidal Wetland Mitigation EffortsDaniels, W. Lee; Perry, James E.; Whittecar, G. Richard; Fajardo, Gariela; Bergschneider, Cara; Despres, Aaron (Virginia Center for Transportation Innovation and Research, 2005-06)Construction of created wetlands to mitigate for highway impacts requires more than $100,000 per ha of impacts. A detailed study of soil, hydrology, and vegetation at 10 recently constructed non-tidal mitigation sites indicates excessive soil compaction and a lack of organic matter continue to limit mitigation success. Detailed hydrologic studies at two mitigation sites (Charles City and Sandy Bottom) point out significant differences in their hydrologic regime vs. adjacent natural wetlands related to soil reconstruction procedures. Results from two compost amendment experiments at Charles City indicate that approximately 100 Mg/ha of organic amendment is optimal for reconstructing hydric soil conditions when natural organic enriched soil materials cannot be returned. Overall mitigation success would improve from (1) utilization of appropriate organic amendments, (2) tillage/ripping protocols at all sites to meet target density specifications, and (3) reconstruction of a soil-geologic profile that is similar in texture and permeability to natural wetland soils. These reconstruction guidelines will help ensure that VDOT complies with existing mitigation regulations in the most cost-effective manner.
- Evaluation of Methods to Calculate a Wetlands Water BalanceDaniels, W. Lee; Cummings, Angela R.; Schmidt, Mike; Fomchenko, Nicole; Speiran, Gary K.; Focazio, Mike; Fitch, G. Michael (Virginia Center for Transportation Innovation and Research, 2000-08)The development of a workable approach to estimating mitigation site water budgets is a high priority for VDOT and the wetlands research and design community in general as they attempt to create successful mitigation sites. Additionally, correct soil physical, chemical and biological properties must be restored that are appropriate to the intended wetlands biota in order for the sites to function similar to a natural sites that they are replacing. The major objectives of this research program were to evaluate the currently recommended procedures for estimating wetland water balances and to characterize the soil and hydrologic regime present at natural and constructed sites and their interaction with wetlands biota. This report records our efforts to develop an estimated overall water budget at VDOT's Ft. Lee mitigation site along with a summary of our previous water budget studies at Manassas. Detail on supporting studies is also provided along with an overall summary of multi-year research results and implications. In this report, the terms water balance and water budget are used almost interchangeably. In our view, however, water budgets are developed by humans to interpret actual wetland water balances. It was concluded that the use of the Pierce (1993) approach for developing mitigation wetland water budgets is prone to a number of errors in surface water charging estimates and ET estimates via the Thornthwaite method. The Pierce approach is most appropriate for estimating water budgets in surface water driven emergent/shrub-scrub systems with little ground water flux that rely upon berms or other water control structures to detain and pond water over impermeable soils or strata. Additionally it was found that the development of soil redox features, particularly the quantity and distinctness of oxidized rhizospheres can be reliably used to interpret hydric soil development sequences in mitigation wetlands. However, the reestablishment of an appropriate mitigation site wetness regime to one that appears to meet jurisdictional wetness criteria will not always guarantee the success of desirable hydrophytic vegetation over time.